[Solved - high home HVAC use] Crazy electric bills from home charging. Is charger function to blame?

[R1SFamilyGuy]

My usual electric usage was almost tripled in my most recent bill ~3000 kWh. in the same period, I've charged around 500kWh

I have not added anything new that could increase usage so much - sure it was hot several days but no way my AC ate this much.

This isn’t my first bill since the charger install but my usage has had an uptick because of a couple of road trips.

the only reason I can think of is my charging schedule - it was only on my Rivian and not at the charger level AND me leaving it plugged in past the scheduled time - sometimes for a whole day. During this time I’ve also had to deal with a few things at home and left the car plugged in and in the garage.

but is that how it would work? I have added the same schedule to my ChargePoint HomeFlex now but without it, does it continue to draw power if plugged in and Rivian just doesn’t use it? Doesn’t make any sense to me!

anyone can think of anything else? I’m also working with my utility company to figure this out.

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[Dark-Fx]

Check outside your house to see if a neighbor is running an extension cord from one of your outlet?

 

[Vantripping]

Do the math: kWhs added multiplied by your electricity rate equals cost to charge. My average rate is about $.16 per kWh so when I add 50 kWhs, or about 35% of my battery capacity, it costs me about $8. Being that takes me about 100 miles, that costs about $.08/mile, which is lower than any of the dozens of cars I've owned and tracked every expense on, including a Prius.

Your electricity rate may vary with time (Time of Use rate), so best to charge when costs and electricity demand are lower, such as late evening, night or morning.

 

[LivingInKaos]

You wouldn't use that much above what you've charged even if it was plugged in and the door left open keeping the HVAC running constantly. You have something else eating your power.

 

[Vantripping]

Do the math: kWhs added multiplied by your electricity rate equals cost to charge. My average rate is about $.16 per kWh so when I add 50 kWhs, or about 35% of my battery capacity, it costs me about $8. Being that takes me about 100 miles, that costs about $.08/mile, which is lower than any of the dozens of cars I've owned and tracked every expense on, including a Prius.

Your electricity rate may vary with time (Time of Use rate), so best to charge when costs and electricity demand are lower, such as late evening, night or morning.

Air conditioning uses a tremendous amount of electricity, as it's usually a 50 amp, 240 volt load, and runs at that level for several hours per day to over half each day, whereas you're likely only charging your car at this rate for at most a few hours per week. So costs of $10 to $20/day are very likely, especially when during peak electricity demand and rate periods, when electricity prices can exceed $.30 to .50/kWh.

 

[COdogman]

Did you add an electric blast furnace that you forgot about? ?‍

 

[NY_Rob]

Op, how are you determining how much energy your Rivian used for the utility billing period? Also, our utility used to estimate our bill when they didn't have the chance to actually come and read our meter. Is it possible you received an "estimated" reading bill from your utility?

 

[MrMusAddict]

My usual electric usage was almost tripled in my most recent bill ~3000 kWh. in the same period, I've charged around 500kWh

I have not added anything new that could increase usage so much - sure it was hot several days but no way my AC ate this much.

This isn’t my first bill since the charger install but my usage has had an uptick because of a couple of road trips.

the only reason I can think of is my charging schedule - it was only on my Rivian and not at the charger level AND me leaving it plugged in past the scheduled time - sometimes for a whole day. During this time I’ve also had to deal with a few things at home and left the car plugged in and in the garage.

but is that how it would work? I have added the same schedule to my ChargePoint HomeFlex now but without it, does it continue to draw power if plugged in and Rivian just doesn’t use it? Doesn’t make any sense to me!

anyone can think of anything else? I’m also working with my utility company to figure this out.

Just to dispel one unsaid concern of your post:

Your charger will only pull energy to charge your car, plus a tiny amount of energy to keep the LEDs and WIFI running on it. For reference, a Raspberry Pi with WiFi runs at around 2 watts, so that's like 10-15 kWh per year.

The other thing that could have increased your power bill's cost is if your provider had peak hours, and you were charging during peak hours. But, you said your kWh consumption tripled, which implied that you aren't on peak charging and your usage just went up.

Given these two things, either you driven/charged 2000 kWh on your Rivian (~5k miles), or there's something else costing you. My money's on the AC. If I didn't have my solar offsetting it, I'd regularly be using over 75 kWh a day just to live in my house during the summer. Add regular charging in there, and I can easily see you breaking 3000 kWh in a month.

 

[Polar]

Your ChargePoint will report to you exactly how much consumption - have you checked validated in that app?

 

[R1SFamilyGuy]

provider had peak hours, and you were charging during peak hours

I do have peak hour rates and I have Rivian scheduled to charge at nob-peak hours. My concern was it was still plugged in during peak hours.

Do the math: kWhs added multiplied by your electricity rate equals cost to charge.

how are you determining how much energy your Rivian used for the utility billing period

I think I have variable pricing too which is why I am trying to just focus on usage. My usage for this bill is 3079kWh.
My usage for charging (just the R1S) was 540kWh. (Cross verified wattage from Rivian and Chargepoint apps’ history)

Add regular charging in there, and I can easily see you breaking 3000 kWh in a month.

My max usage for this season, based on history (without EV) is 900-1000 kWh. So, no I don’t think so.

Is it possible you received an "estimated" reading bill from your utility

Good point but yes and no. The end reading of last month was estimated but this month’s is actual. The few months before that have been actuals too. Even by combining last two months (so going by actuals), the numbers don’t seem right (again, considered actual kWh usage reported by charger/Rivian apps)

 

[R1SFamilyGuy]

Check outside your house to see if a neighbor is running an extension cord from one of your outlet?

Unless there is an underground
/hidden outlet of sorts, I should be good here. I mean, I didn’t think to check that, good call, but no..

Did you add an electric blast furnace that you forgot about?

No

 

[R1SFamilyGuy]

Your ChargePoint will report to you exactly how much consumption - have you checked validated in that app?

Yeah, Chargepoint reported accurate to 0.01 units which Rivian was rounding off but otherwise they match

 

[mikehmb]

I’d go out and watch your meter, which is almost as exciting as watching paint dry. See if you can identify a spike in usage correlation to … <gestures broadly> something. I’d also specifically check your home AC compressor consumption.

An EVSE shouldn’t be pulling current if the onboard charger can’t accept it - there’s literally nowhere for it to go. So if the truck is saying it only too 500kWh, I would be inclined to believe it.

 

[Mellowyellow]

Even if you adjusted your house AC a few degrees lower that could do it too

 

[Tony R1S]

My usual electric usage was almost tripled in my most recent bill ~3000 kWh. in the same period, I've charged around 500kWh

I have not added anything new that could increase usage so much - sure it was hot several days but no way my AC ate this much.

This isn’t my first bill since the charger install but my usage has had an uptick because of a couple of road trips.

the only reason I can think of is my charging schedule - it was only on my Rivian and not at the charger level AND me leaving it plugged in past the scheduled time - sometimes for a whole day. During this time I’ve also had to deal with a few things at home and left the car plugged in and in the garage.

but is that how it would work? I have added the same schedule to my ChargePoint HomeFlex now but without it, does it continue to draw power if plugged in and Rivian just doesn’t use it? Doesn’t make any sense to me!

anyone can think of anything else? I’m also working with my utility company to figure this out.

Do you have a smart meter, or manual meter? If it's a manual meter, I'd suspect the meter readings. I had an issue where my water bill jumped up as if I had a leak and my water use was 10x my average. It turns out that for past year, the meter reads were incorrect (avg 10 gals /day), so I got slammed with a corrected reading which made it look like I had a leak. I didn't notice, because the $ amount I paid was still the same regardless of the low use. So in short, check if your previous bills make sense based on your ev charging use.

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